Chemical feed pump



June 21, 1955 C. B. MOLLER CHEMICAL FEED PUMP Filed Feb. 20, 1951 zaga.

vlll

III

inited States Patent 2,711,137 Patented .lune 21, 1955 This invention relates to improvements in a chemical feed pump particularly adapted for use in a water purification system in which the Water purification chemical is fed in small quantities at a predetermined rate into the water line. Pumps of this type should be designed for long periods of continuous service with little attention.

If the pumping member is a solid piston, it is diilicult to lubricate the piston and to maintain a tight seal to prevent leakage of the chemical into the pumping mechanism. On the other hand, if the pumping member is a flexible diaphragm, the diaphragm will have a relatively short life and must be replaced.

It is an object of my invention to combine the advantages of the solid piston and diaphragm by providing a solid pumping member with a seal to prevent leakage of the chemical and to further provide a diaphragm connected to the piston and to the pump housing in back of the piston so that any tluid that may leak past the seal may be trapped.

Further objects and advantages of my improvements will be more readily apparent from the following description of a preferred embodiment thereof as illustrated in the attached drawings, in which:

Fig. 1 is a side elevation of the pump casing;

Fig. 2 is a top plan View thereof; and

Fig. 3 is a fragmentary vertical section on an enlarged scale taken on the plane indicated 3 3 in Fig. 1.

The housing 1) encloses the conventional mechanism for operating the pump. The piston rod 12 is mounted in the bearing 14 and is reciprocated by suitable mechanism in the housing 10. The piston head 16 preferably made of glass forms the pumping member. The cylindrical wall 13 extending from the housing 10 encloses the piston rod 12. On the outer end of the cylindrical wall 18 is mounted a ring-shaped member 26, to which is attached a pump casing 30. pumping chamber 28, and has an inlet passage 32 and an outlet passage 34 communicating with this chamber. An inlet valve 36 is mounted in the inlet passage, and an outlet valve 38 is mounted in the outlet passage. The piston head 16 projects into chamber 28 and is surrounded by a packing ring 40 held in place by a retainer ring 42.

A flexible diaphragm 22 is mounted between wall 18 and ring member 26. This diaphragm has a marginal rim 22a, which is clamped between member 26 and wall 18, and a central portion 24 which is connected in a fluidtight manner to the back of the piston head 16. This diaphragm divides the enclosure formed by casing 30, member 26, wall 18, and the side of housing 10, into two compartments 44 and 20. Compartment 44 is filled with lubricant and communicates at the top with an open relief tank 46 which receives the excess lubricant as diaphragm 22 is llexed to the left. Compartment 20 is ordinarily empty and has an opening 47 at the bottom.

The lubricant in the compartment 44 serves to lubricate the piston pumping member 16. If the corrosive chemical being pumped leaks past the packing 40 it will The latter contains a be trapped in the lubricant compartment and an overllow from the relief tank 46 indicates that the packing 40 should be replaced.

The diaphragm 22 is not subjected to the pressure of the pumping chamber and should have a relatively long life. If the diaphragm should fail, the lubricant and any chemical which leaks past the packing will pass into the compartment 20 and run out through the opening 47 at the bottom of the compartment 20. The chemical will therefore not corrode the operating mechanism for the pump.

I claim:

1. In a chemical feed pump,

having a closed housing provided with a bearing,

a piston rod projecting through said bearing, and a piston mounted on the outer end of the rod, the housing containing a pumping mechanism adapted to reciprocate said piston rod: a wall attached to said housing and surrounding said rod; a pump casing mounted on the outer end of said wall and forming, with said wall and said housing, an enclosure around said rod, said casing containing a pump chamber and said piston projecting into said chamber; a packing between said piston and said casing forming a seal around said piston between said chamber and said enclosure; and a ilexible diaphragm, having a central portion attached to the back of said piston and a marginal rim attached to said wall, said diaphragm dividing said enclosure into two compartments, the compartment adjoining said casing being adapted to receive lubricant and to trap iluid leaking past said packing and having means for relieving pressure of the lubricant on the diaphragm, and the compartment adjoining said housing having a drain outlet for escape of iluid in case of rupture of said diaphragm.

2. In a chemical feed pump,

having a closed housing provided with a bearing,

a piston rod projecting through said bearing, and a piston mounted on the outer end of the rod, the housing containing a pumping mechanism adapted to reciprocate said piston rod; a tubular wall projecting from said housing concentric with said bearing and spaced therefrom; a pump casing secured to the outer end of said wall, said casing containing a pumping chamber and having a circular opening, concentric with said rod, leading to said chamber, said piston being disposed to reciprocate through said opening; a packing around said opening forming a seal around said piston; a flexible diaphragm having a marginal rim sealed to said tubular wall, and a central portion sealed to said piston, said diaphragm dividing the space enclosed by said wail into a first and a second compartment, the first compartment, that adjoining said casing, being adapted to hold lubricant, and the second compartment having'a drain outlet for escape of fluid in case of rupture of said diaphragm; and a tank for lubricant having an opening communicating with said ilrst compartment, Vsaid tank being adapted to receive overflow from said rst compartment as the diaphragm is carried by the piston toward said chamber and to store excess lubricant for refilling said first compartment upon motion of the diaphragm in the opposite direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,565,029 Spreen Dec. 8, 1925 1,670,799 Dornbirer May 22, 1928 2,191,861 Rymal Feb. 27, 1940 2,202,351 Loweke May 28, 1940 2,219,566 Sauzedde Oct. 29, 1940 2,326,474 Malsbary Aug. 10, 1943 2,405,093 La Brie July 30, 1946 2,572,952 Rymal Oct. 30, 1951 

